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| United States Patent |
5,792,180
|
|
Munoz
|
August 11, 1998
|
High bend strength surgical needles and surgical incision members and
methods of producing same by double sided photoetching
Abstract
There is provided a high bend strength double pointed surgical needle, or
surgical incision member, which includes a suture hole intermediate the
points and a pair of crimping bulges adjacent the suture hole. The high
strength surgical needle further includes transverse slots adjacent each
pointed end. There is also disclosed a method of forming a plurality of
high bend strength surgical needles from a sheet of needle stock including
coating both sides of the sheet of needle stock with a photoresist,
exposing both sides of the sheet of needle stock to light in the image of
a plurality of surgical needle blanks connected at either pointed end to
carrier strips, subjecting the sheet so exposed to an etchant to remove
all unexposed metal and removing the surgical needle blanks from the sheet
| Inventors:
|
Munoz; Marcelino P. (Waterbury, CT)
|
| Assignee:
|
United States Surgical Corporation (Norwalk, CT)
|
| Appl. No.:
|
590256 |
| Filed:
|
January 23, 1996 |
| Current U.S. Class: |
606/223; 430/320 |
| Intern'l Class: |
A61B 017/06 |
| Field of Search: |
430/320,317,313,323
606/222,223
|
References Cited
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| 2479464 | Aug., 1949 | Bliss.
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| 2735763 | Feb., 1956 | Heath.
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| 3038475 | Jun., 1962 | Orcutt.
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| 3054172 | Sep., 1962 | Turney, Jr.
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| 3162871 | Dec., 1964 | Powers.
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| 3348669 | Oct., 1967 | Powers.
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| 3358363 | Dec., 1967 | Jacks et al.
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| 3551227 | Dec., 1970 | Burgess.
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| 3808001 | Apr., 1974 | Konstantouros et al.
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| 3816273 | Jun., 1974 | Synder.
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| 3822461 | Jul., 1974 | Malmstrom.
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| 3942981 | Mar., 1976 | Sato.
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| 4080709 | Mar., 1978 | Poler.
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| 4215194 | Jul., 1980 | Shepherd.
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| 4282311 | Aug., 1981 | Dinardo, Jr.
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| 4587202 | May., 1986 | Borysko.
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| 4672734 | Jun., 1987 | Kawada et al.
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| 4711800 | Dec., 1987 | DiVincenzo.
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| 4777096 | Oct., 1988 | Borysko.
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| 4785868 | Nov., 1988 | Koenig, Jr.
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| 4793218 | Dec., 1988 | Jordan et al.
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| 4842969 | Jun., 1989 | Kawatsuki et al.
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| 4890614 | Jan., 1990 | Kawada et al.
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| 4960659 | Oct., 1990 | Sagou | 430/323.
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| 5001323 | Mar., 1991 | Matsutani et al.
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| 5057401 | Oct., 1991 | Borysko et al.
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| 5178628 | Jan., 1993 | Otsuka et al.
| |
| 5330441 | Jul., 1994 | Prasad et al.
| |
| 5403344 | Apr., 1995 | Allen.
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| 5411613 | May., 1995 | Rizk et al.
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| 5478344 | Dec., 1995 | Stone et al.
| |
| Foreign Patent Documents |
| 24 05 998 A1 | Feb., 1974 | DE.
| |
| 27 37 648 A1 | Aug., 1977 | DE.
| |
| 34 14 262 A1 | Apr., 1984 | DE.
| |
Primary Examiner: Buiz; Michael
Assistant Examiner: Lewis; William W.
Claims
What is claimed is:
1. A method of producing a surgical needle blank comprising the steps of:
(a) coating opposite sides of a metal sheet with a light sensitive
photoresist;
(b) exposing the photoresist with light in the image of a plurality of
surgical needle blanks, each needle blank having opposed pointed ends,
wherein the light image includes at least one carrier strip and a
plurality of surgical needle blanks attached at at least one of their
pointed ends in spaced relationship to the strips;
(c) removing unexposed photoresist, to thereby leave in place on the metal
sheet hardened photoresist in the image of a plurality of surgical needle
blanks attached to the carrier strips; and
(d) exposing the product of step c to an etchant to remove metal not
protected by the hardened photoresist, to thereby form a plurality of
surgical needle blanks having opposed pointed ends and attached at at
least one of the pointed ends to a carrier strip.
2. The method according to claim 1, wherein the step of exposing the
photoresist with light includes exposing the photoresist with light in the
image of a plurality of surgical needle blanks, each needle blank image
having an opposed pair of crimping bulges.
3. The method according to claim 1, wherein the step of exposing the
photoresist with light includes exposing the photoresist light in the
image of a plurality of surgical needle blanks, each needle blank image
having a slot adjacent each pointed end.
4. The method according to claim 1, wherein the step of exposing the
photoresist with light includes exposing the photoresist with light in the
image of a plurality of surgical needle blanks, each needle blank image
having a suture hole intermediate the pointed ends.
5. The method according to claim 1, further comprising the step of drilling
a suture hole through the surgical needle blanks.
6. The method according to claim 1, further comprising the step of heat
treating the surgical needle blanks.
7. The method according to claim 1, further comprising the step of
electropolishing the surgical needle blanks.
8. The method according to claim 1, further comprising the step of removing
the surgical needle blanks from the strips.
9. The method according to claim 8, further comprising the step of tumbling
the surgical needle blanks to form surgical needles.
10. The method according to claim 1, wherein the step of exposing the
photoresist includes the step of exposing the opposite sides of the metal
sheet to different images.
11. The method according to claim 1, wherein the sheet includes at least
two carrier strips and the needle blanks are connected to the carrier
strips at both pointed ends.
Description
BACKGROUND
1. Technical Field
This disclosure relates generally to surgical needles, and surgical
incision members used in conjunction with endoscopic or laparoscopic
suturing apparatus, and, more particularly, to high bend strength surgical
needles and methods of producing same by double sided photoetching of
needle stock.
2. Description of Related Art
The production of surgical needles from needle stock is often a complex
process. As used herein the terms "surgical needle blanks" and "surgical
incision member blanks" refer to a piece of needle stock material at
various stages of completion but not fully formed into a surgical grade
needle or incision member suitable for use during surgical procedures.
Various types of methods have been developed to form surgical needle
blanks and needles. These methods include metal working the needle stock
by cutting, stamping, pressing or bending the needle stock to impart the
desired characteristics to the needle blanks or by other methods such as
grinding to remove material from the needle stock. Often these methods
introduce stresses into the needle blanks which may tend to weaken the
needle blanks slightly. The strength of a finished surgical needle is
particularly important where the surgical needle may be subject to bending
forces during use, which forces, if high enough, may permanently deform
the surgical needle. The bend strength of needles can be tested by
measuring the bend moment or the degree of deflection of the needles when
subject to predetermnined loads and bend or rotational distances, without
suffering permanent deformation.
Certain complex surgical needles may require several operations to fully
form the needles. One such type of needle, a surgical incision member
disclosed in U.S. patent application Ser. No. 08/260,759, filed Jun. 16,
1994, and entitled SURGICAL INCISION MEMBERS, the disclosure of which is
incorporated by reference herein, is a double pointed surgical needle
having suture attachment structure intermediate the points. Preferably,
the suture attachment structure is a suture hole with crimping bulges
formed on opposed sides of the suture hole. Additionally, the surgical
incision member may include apparatus engagement structure in the form of
slots adjacent each pointed end which cooperate with a suitable surgical
suturing apparatus such as that disclosed in U.S. patent application Ser.
No. 08/293,233, filed Aug. 19, 1994, entitled SURGICAL SUTURING APPARATUS
WITH LOADING MECHANISM. At each stage of formation of a complex surgical
needle, such as the aforementioned surgical incision member, there is a
chance that stresses may be induced into the needle blank either
mechanically by stamping, cutting, etc., or thermally by grinding or even
laser drlling or cutting of the needle blank.
Often the stresses introduced into the needle blanks are insufficient to
weaken the needle blank enough to cause difficulties with the finished
surgical needle during use. When used in sutuing tough tissues, however,
it may be desirable to have an extra margin of strength designed into the
needle to prevent bending of the needle during use. One way this may be
accomplished is by increasing the dimensions of certain areas of the
needle, particularly the center section of the needle body. However, the
formation of such needles may still lead to mechanically and/or thermally
induced stresses in certain critical areas of the needles. One method of
forming surgical needles generally, and without mechanical operations, is
by a process known as photoetching, such as that disclosed generally in
U.S. Pat. Nos. 4,587,202; 4,777,096; and 5,057,401. These processes
generally include coating a sheet of needle stock with a light sensitive
and etchant resistant chemical, or photoresist, and exposing the coated
sheet to light images in the form of needle blanks. The exposed
photoresist hardens in the shape of the images and the unexposed
photoresist is removed. The sheet is then subjected to an etchant which
removes all the exposed metal of the sheet leaving only the needle blanks
in the shape of the images. While the above described process is known, it
is typically used only for relatively simple needle structures having a
single pointed end. Upon breaking the needle blanks free of the stock
material suture attachment structure may be formed at the end of the
needle opposite the tip, such as by mechanical or laser drilling a hole or
mechanical channeling, which may introduce stresses.
SUMMARY
A method is disclosed for simultaneously forming a plurality of high
strength surgical needles, such as surgical incision members, from needle
stock. The method generally includes coating both sides of a sheet of
needle stock with a photoresist The coated sheet is then exposed on a
first side to light in the image of a plurality of double pointed surgical
needle blanks connected to one or more carrier strips at at least one
pointed end. Preferably, the image additionally includes suture attachment
structure in the form of a suture hole intermediate the points and
crimping bulges extending outwardly from the body portion of the needle
blank adjacent the suture hole area. Additionally, apparatus engagement
structure in the form of transverse slots adjacent either pointed end may
also be provided in the image. A second side of the coated sheet is also
exposed to light in the image of a plurality of surgical needle blanks,
which images preferably are in register with the images on the first side
of the sheet. The images on the second side of the sheet may include all
or just some of the features of the images on the first side of the sheet.
Once the sheet has been exposed on both sides to light in order to harden
the photoresist into images of a plurality of surgical needle blanks
connected at each pointed end to carrier strips, the sheet is dried by
baking at suitable temperatures which further serves to harden the exposed
photoresist. The sheet is then subjected to a developer which removes the
unexposed photoresist. The sheet, coated with the images of a plurality of
surgical needle blanks connected by carrier strips, is then subjected to
an etch bath which removes all of the uncoated needle stock. The result is
a sheet containing a plurality of rows of double pointed surgical needle
blanks connected at one or both pointed ends to the carrier strips. The
sheet is then rinsed and may be heat treated to further strengthen the
needle blanks. The surgical needle blanks are then either removed by
mechanical means or by etching them free from the carrier strips.
Preferably, once the needle blanks have been removed they are tumbled in a
suitable tumbling media, for example, cut cylinders of aluminum oxide
followed by tumbling in porcelain balls, to finish the pointed ends to a
desired predetermined radius. Details of tumbling pointed needles to
obtain the desired radius of curvature at the point of a needle are
disclosed and claimed in U.S. patent application Ser. No. 08/325,847,
filed Oct. 19, 1994, the disclosure of which is incorporated by reference
herein. Also see U.S. Pat. No. 5,447,465.
There is also disclosed a sheet of surgical needle blanks including a
plurality of double pointed surgical needle blanks connected at either
pointed end to needle stock. Each needle blank includes suture attachment
structure in the form of a suture hole intermediate the pointed ends and a
pair of crimping bulges adjacent either side of the suture hole. Each
needle blank further includes apparatus engagement structure in the form
of transverse slots adjacent either pointed end.
There is also disclosed a high bend strength surgical needle. The surgical
needle is a curved, double pointed needle having a suture hole
intermediate the points and crimping bulges formed on either side of the
suture hole. The surgical needle further includes transverse slots formed
adjacent each pointed end. The surgical needle is preferably formed of
Carpenter 455 series stainless steel such as that disclosed in U.S. Pat.
No. 5,411,613.
BRIEF DESCRIPTION OF THE DRAWINGS
Various embodiments are described hereinbelow with reference to the
drawings, wherein:
FIG. 1 is a plan view of a sheet of surgical incision member blanks formed
according to the disclosed process;
FIG. 2 is an enlarged partial plan view of one of the photomasks used in
forming images on a first side of the sheet of surgical incision member
blanks of FIG. 1;
FIG. 3 is an enlarged partial plan view of a second photomask used in
forming images on a second side of the sheet of surgical incision member
blanks of FIG. 1;
FIG. 4 is an enlarged perspective view of a portion of the sheet of
surgical incision member blanks of FIG. 1;
FIG. 5 is an enlarged perspective view of a single surgical incision member
blank separated from the sheet of FIG. 4;
FIG. 6 is side plan view of a surgical incision member after tumbling; and
FIG. 7 is a perspective view of the surgical incision member of FIG. 6.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to the drawings and initially to FIG. 1 there is shown a
sheet 10 of high bend strength surgical incision member blanks,
hereinafter "needle blanks" formed according to the disclosed method.
Sheet 10 includes a plurality of rows of needle blanks 12 attached to
parallel rows of carrier strips 14 extending across sheet 10. Needle
blanks 12 may be attached to two carrier strips 14 as shown in row of
needle blanks A or only to a single carrier strip 14 as shown in row of
needle blanks B. Each needle blank 12 has a body portion 16 and a pair of
opposed pointed end portions 18. When needle blanks 12 are attached to two
carrier strips 14, as in row A, needle blanks 12 are preferably attached
to carrier strips 14 at each pointed end portion 18. However, when needle
blanks 12 are attached only to a single carrier strip 14, as in row B,
needle blanks 12 are preferably attached to carrier strip 14 at only one
of the pointed end portions 18. Preferably, body portion 16 of each needle
blank 12 includes a suture hole 20 and a pair of opposed crimping bulges
22 extending outwardly of body portion 16 and adjacent suture hole 20.
Body portions 16 may also include apparatus engagement structure, in the
form of slots 24, formed in body portions 16.
Sheet 10 is generally formed from a sheet of suitable needle stock, such
as, plastics, steels, composites, etc. The needle stock is coated on both
sides with a suitable photoresist and exposed to light in the image of the
needle blanks and carrier strips to harden the photoresist. The remaining
unhardened photoresist is then removed and the coated needle stock is
exposed to an etchant which removes all the uncoated needle stock. The
result is sheet 10 including needle blanks 12 and carrier strips 14.
During the etching process, the etchant "eats" substantially into the face
of the unexposed needle stock, however, some lateral etching may also
occur and may be compensated for, and even manipulated to beneficial use.
In order to expose the needle stock coated with photoresist to light in the
image of the needle blanks and carrier strips, the light is shown through
a negative image, or photomask, of the needle blanks and carrier strips.
The photomask is typically made of glass for repeated use. By manipulating
the characteristics of the photomask the characteristics of the resultant
needle blanks and carrier strips may be controlled. When different
characteristics are desired on opposed sides of the needles different
masks may be used in exposing the photoresist on opposite sides of the
needle stock to light
Referring now to FIG. 2, a first photomask 26 includes both positive and
negative image areas which correspond to needle stock to remain and be
removed, respectively. Positive areas include body portion images 28 which
correspond to body portion 16. Photomask 26 also includes pointed end
images 30 and strip images 32 corresponding to pointed end portions 18 and
carrier strips 14, respectively. As shown, pointed end images 30 and strip
images 32 are connected so that the resultant needle blank 12 is connected
to carrier strips 14 at both pointed ends 18. Obviously, where only one
pointed end 18 and carrier strip 14 connection is desired, the photomask
can be so modified. Photomask 26 may also include enlarged areas of body
portion image 28, or bulge images 24, which correspond to crimping bulges
22.
In order to remove material from the metal sheet, certain areas of
photomask 26 are left covered up, i.e., negative images. For example, in
order to form suture hole 20 in needle blank 12, a suture hole image 36 is
positioned intermediate bulge images 24. Similarly, slot images 28,
corresponding to slots 24, are provided in photomask 26 adjacent pointed
end images 30.
As noted above, different photomasks may be used on opposite sides of the
needle stock where differing characteristics are desired on opposed sides
of the needle blanks. Thus, where slots 24 are desired on only one side of
the needle blanks, a second photomask without slot images 38 is used in
exposing the opposing side of the needle stock to light
Referring now to FIG. 3, a second photomask 40 is substantially identical
to photomask 26 with the exception of the absence of slot images 38.
Photomask 40 includes body portion images 42 and pointed end images 44
connected to strip images 46. Photomask 40 also includes bulge images 48
as well as a suture hole image 50. Photomask 40 is preferably dimensioned
and configured to register exactly with photomask 26 in order to form
uniform rows of needle blanks. For example, suture hole images 36 and 50
are lined up exactly opposite each other.
In order to form sheet 10 containing high strength surgical needle blanks
12 using the disclosed photomasks 26 and 40 a sheet of suitable strength
metal is used, such as, for example, Carpenter 455 stainless steel
disclosed in U.S. Pat. No. 5,411,613. The particular needle stock used is
chosen based on its strength and use characteristics which, as described
in more detail hereinbelow, may be increased by prior metal working and/or
subsequent heat treating.
The general and specific compositions of preferred martensitic
precipitation-hardening stainless steels are as shown on Table I:
TABLE I
__________________________________________________________________________
WEIGHT PERCENTS
GENERAL PREFERRED
CARPENTER
STAINLESS CUSTOM
SANDVIK
ELEMENT
COMPOSITION
COMPOSITION
455 W 17-4 PH
15-5 PH
PH 13 MO
450 1RK91
__________________________________________________________________________
Fe Balance Balance Balance
Balance
Balance
Balance
Balance
Balance
Balance
Cr 10-17 11-13 11.0-12.5
16.5 16.0 15.0 12.5 15.0 11.7
Ni 4-11 7-10 7.5-9.5
6.75 4.0 4.0 8.0 -- 9.1
Ti 0-1.6 0.8-1.4 0.8-1.4
0.8 -- -- -- -- 1.0
Mo 0-6 0.5-4.5 0.50 -- -- -- 2.5 1.0 4.1
Cu 0-4 1-3 1.5-2.5
-- 3.2 4.0 -- 0.75 2.0
C <0.02-0.07
0.015-0.06
0.05 0.07 0.04 0.07 0.05 0.05 .004
Mn 0.5-0.6 <0.5-0.6
0.50 0.5 0.25 -- 0.5 -- .17
Si <0.5-1 <0.5-0.6
0.50 0.5 0.60 -- 0.5 1.0 .05
P 0-0.2 0-0.04
0.04 -- -- 0.20 -- -- --
S 0-0.04
0-0.04
0.03 -- 0.01 -- -- -- .002
Nb 0-0.5 0-0.5 0.10-0.50
-- -- -- -- 0.40 --
Ta -- -- -- -- -- -- -- -- --
Al 0-1.1 0 -- 0.4 -- -- 1.1 -- --
Nb + Ta
0-0.6 0 -- -- 0.25 0.35 -- -- --
Cobalt
0-6 0-3 -- -- -- -- -- --
__________________________________________________________________________
Most preferably, the alloys contain a nickel-titanium (Ni.sub.3 -Ti)
precipitation hardening phase. Preferably, such an alloy contains about 4
to about 11 weight percent nickel and about 0.0 to about 1.6 weight
percent titanium, more preferably about 7 to about 10 weight percent
nickel and about 0.8 to about 1.4 weight percent titanium.
A preferred alloy is 455 steel. This 455 stainless steel contains about 11
to about 12.5 weight percent chromium, about 7.5 to about 9.5 weight
percent nickel, about 0.8 to about 1.4 weight percent titanium, about 0.5
to about 0.7weight percent molybdenum, about 1.5 to about 2.5 weight
percent copper, about 0.04 to about 0.06 weight percent carbon, about 0.4
to about 0.6 weight percent manganese, about 0.4 to about 0.6 weight
percent silicon, up to about 0.04 weight percent phosphorus, about 0.02 to
about 0.04 weight percent sulfur, about 0.1 to about 0.5 weight percent
niobium, with iron as the remainder.
A class of precipitation hardenable alloys are disclosed by PCT Application
WO 93/07303, incorporated herein by reference. This PCT application
discloses a precipitation hardenable martensitic stainless steel alloy
comprising, in percent by weight, about 10% to about 14% chromium, between
about 7% to about 11% nickel, molybdenum between about 0.5% to about 6%,
cobalt up to about 6%, copper between about 0.5% to about 4%, aluminum
added up to about 0.6%, titanium between about 0.4% and about 1.4%, carbon
and nitrogen not exceeding about 0.05%, with iron as the remainder and the
content of any other element of the periodic table not exceeding about
0.5%. Preferably, the alloy has about 0.5% to about 3% copper, up to about
6% cobalt, and about 0.5% to about 4.5% molybdenum. More preferably, the
alloy has up to about 3% cobalt. Most preferably, this stainless steel
comprises about 11.5 to about 12.5 weight percent chromium, about 8.5 to
about 9.5 weight percent nickel, about 0.8 to about 1.0 weight percent
titanium, about 3.5 to about 4.5 weight percent molybdenum, about 0.5 to
about 2.5 weight percent copper, up to about 0.02 weight percent carbon,
up to about 0.5 weight percent manganese, up to about 0.5 weight percent
silicon, up to about 0.02 weight percent sulfur, with the remainder
consisting essentially of iron. A preferred martensitic
precipitation-hardening alloy for use in the present invention is
1RK91.TM. steel, developed by A. B. Sandvik Steel, S-811 81 Sandviken,
Sweden.
Preferably, the sheet of metal has a thickness of approximately 0.030 to
0.040 inches.
The sheet of metal is coated on both sides with a chosen photoresistive
material, such as KMER or RISTON, available from DuPont, using known
methods. The coating is then dried by heating for a predetermined time at
a low temperature.
Once the coating has dried, photomasks 26 and 40, either singly or
simultaneously, are overlayed over the coated sheet in correct register.
Various indicia may be provided on photomasks 26 and 40 to ensure accurate
alignment and register. The photomasked sheet is exposed to a suitable
light source, such as an ultraviolet rich light to harden the photoresist
in the images of the needle blanks and carrier strips. The photomasks are
removed and the unexposed photoresist is removed by subjecting the plate
to a suitable developer designed for use with the particular photoresist
chosen. The remaining photoresist may be further hardened by baling the
sheet at 200-300 degrees Fahrenheit for approximately 10 minutes. The
result is a solid metal sheet coated with etchant resistant photoresist in
the images of needle blanks 12 and carrier strips 14.
The coated sheet is then subjected to an etch bath, preferably as 36 to 42
degrees Celsius Baume aqueous ferric chloride, or an aqueous solution of
hydrochloric acid and either ferric chloride or nitric acid, where the
metal is dissolved from the areas not covered by the etchantresistant,
photo-sensitive material 120. The sheet is immersed just long enough so
that approximately 50% of the thickness of metal 130 on each side is
etched away for approximately minutes. The etch bath chemically etches or
removes the areas of the metal sheet not protected by the hardened
photoresist. As noted above, the etching process is progressive and etches
away laterally on the surface as well as into the face of the exposed
metal. Once the fully etched sheet 10 is removed from the etch bath it is
rinsed to neutralize any remaining etchant. The etched sheet 10 may then
be subjected to a suitable stripper to remove the hardened photoresist and
rinsed again.
Referring now to FIG. 4, the resultant needle blanks 12 have a generally
rectangular or "beam" cross-section which further increases the bend
strength of the finished needles. By varying the etch bath composition and
duration, the degree of lateral etching to round the edges and shape of
the cross-section of the needle blank can be controlled while generally
retaining the strength advantages of a beam construction without attendant
compressing of the needle stock. Additionally, the depth of the suture
hole etched in both sides of the needle blank can be adjusted to etch
completely through the needle blank or only as a pilot hole on one or both
sides for further mechanical or laser drilling. As shown, needle blank 12
includes body portion 16 connected to carrier strips 14 at each of the
pointed end portions 18. Crimping bulges 22 are adjacent suture hole 20
and slots 24 are adjacent each pointed end portion 18. Further, sheet 10
may be subjected to a second diluted etch bath to further refine or "mill"
the needle blank shape. The additional etch step may also polish the
suture holes and slots.
Prior to removing the needle blanks from the carrier strips the entire
sheet 10 may be heat treated to further strengthen the needle blanks.
Preferably, sheet 10 is heat treated in the manner disclosed in U.S. Pat.
No. 5,411,613. For example, sheet 10 may be heated at about 400.degree. C.
to about 500.degree. C. for about 30 minutes to 90 minutes, preferably
under vacuum. Additionally, the sheet may be electropolished using known
methods to smooth the outer surfaces of the needle blanks.
Needle blanks 12 may be removed from sheet 10 by several methods. In one
embodiment, an etchant resistive adhesive backing, such as a vinyl
copolymer for example, is affixed to one side of sheet 10 and sheet 10 is
subjected to a mild or diluted etching bath to dissolve the connections
between needle blanks 12 and carrier strips 14. This additional etching
process has the additional advantage of providing the aforementioned
"milling" by smoothing the edges of needle blanks 12 as well as refining
the overall shape. By etching needle blanks 12 free of carrier strips 14
no additional stresses are introduced into needle blanks 12. With needle
blanks 12 individually held on the adhesive backing any number of
additional operations, such as hole drilling, suture attachment, etc., may
be performed on all the needle blanks quickly and simultaneously.
Alternatively, needle blanks 12 may be separated from carrier strips 14 by
conventional methods, such as mechanical or laser cutting or even bending
to break the connections. Any minor stresses introduced into pointed tip
portions 18 connected to carrier strips 14 by these alternative methods
will obviously be localized at pointed tip portions 18 and will not affect
the bend strength of needle blanks 12 to any significant extent.
Referring now to FIG. 5, there is show a single needle blank 12 after
removal from one or more carrier strips 14. As noted above, needle blank
12 has a generally beam shaped configuration which is generally stronger
than a pure round cross sectional shape. Needle blank 12 includes body
portion 16 having pointed end portions 18 at each end thereof. Needle
blank 12 also includes the aforementioned suture hole 20 and crimping
bulges 22. Slots 24 are also provided adjacent each pointed end portion 18
and, preferably, on one side only of needle blank 12.
Once needle blanks 12 have been removed from carrier strips 14, they may be
further smoothed and refined by tumbling them in a suitable tumbling media
for a predetermined time such as disclosed in U.S. Pat. No. 5,447,465.
While tumbling is the preferred method of refinement, it is also within
the contemplated scope of the disclosure to refine the needle blanks by
various other means, such as, for example, by etching. Preferably, the
refining process will be performed in such as manner so as to round or
blunt the pointed tip portions 18 to form tissue penetrating radiused tip
needles as shown in FIGS. 6 and 7. Preferably, the radius imparted to the
needle blank tips is approximately 0.005 to 0.015 inches, and more
preferably 0.007 inches.
Referring now specifically to FIGS. 6 and 7, the finished surgical incision
member 52 has a relatively rounded-off body portion 54 with opposed
pointed tip portions 56. As noted above, preferably pointed tip portions
56 have radiussed tissue penetrating tips 58. Slots 60 are defined in body
portion 54 and are oriented substantially perpendicular to both a
longitudinal axis of body portion 54 and a longitudinal axis of a suture
hole 62. Crimping bulges 64 are formed adjacent suture hole 62.
The resultant surgical needles formed by the above described process have
been tested for bend strength on bend strength testing apparatus such as
that disclosed in U.S. Pat. Nos. 5,022,273 and 5,297,440. The results of
the tests are summarized below.
It will be understood that various modifications can be made to the
embodiments disclosed herein. For example, the connections between the
carrier strips and needle blanks may be located at other non-critical
positions along the body portion other than the pointed tip portions.
Further, as noted above, various other needle stock materials,
photoresists and etchants may be used with similar effect. Additionally,
various other complex structural characteristics, such as, channels, for
example, may be provided for by etching or by further mechanical
processing after removal from the sheet. Therefore, the above description
should not be construed as limiting, but merely as exemplification of
preferred embodiments. Those skilled in the art will envision other
modifications to the disclosure within the scope and spirit of the claims
appended hereto.
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